Apparatus for controlling the drying and evaporation intensity of paper machine cylinders



July 27, 1965 c. ALLANDER ETAL APPARATUS FOR CONTROLLING THE DRYING AND EVAPORATION INTENSITY OF PAPER MACHINE CYLINDERS 2 Sheets-Sheet l Filed Feb. 6, 1962 NN NN LMMN ATTYS.

July 27, 1965 c. ALLANDER ETAL 3,195,556

APPARATUS FOR CONTROLLING THE DRYING AND EVAPORATION INTENSITY OF PAPER MACHINE CYLINDERS Filed Feb. 6. 1962 2 Sheets Sheet 2 FIG. 2.

/7/ /l/,lll l; I w 171,1, l h

i INVENTOR CLAES ALLANDE United States Patent O 3 196556 APPARATUS FOR CONTQOLLING THE DRYING AND EVAPORATION INTENSITY OF PAPER MA- CHINE CYLINDERS Claes Allander, Bromma, and Sven Wallin, Jonkopng,

The present invention relates to a device to control the evaporation intensity in a paper machine by blowing a mixture of air and water vapour against a number of cylinders, the device being constructed in the form of a closed unit wherein a considerable part of the blown mixture of air and vapour is caused to circulate and only a certain part of said mixture is supplied to and conducted away from the unit.

It is previously known to provide cylinders in paper machines with so called hot air hoods equipped with means for blowing heated air or another treatment medium against the web for obtaining a higher evaporation effect. In order to achieve the highest possible increase in capacity, it is desirable to operate with as great an amount of air as possible. It has proved dicult, however, to distribute the supplied air in such a manner that a uniform evaporation is effected across the entire width of the paper web.

lt is an object of this invention to produce a novel and improved construction of such hot air hoods, so that an effective as well as uniform drying of the web is achieved. The invention is characterized in that the blowing is carried out by means of a plurality of openings, each having a hydraulic diameter less than half the distance between the cylinder and said openings, that the mixture of air and vapour is returned to the unit through a plurality of larger openings having a total area of at least three times the total area of the blowing holes, and that the said circulation is maintained by means of one or several centrifugal blowers incorporated in said unit.

The treatment medium is preferably heated by hot gas supplied to the unit through pipes opening at the inlet of the blowers in question, said pipes being preferably provided with valves. According to a suitable embodiment of the invention, the unit is divided by partition walls into a pressure chamber located adjacent to the wall which encloses the cylinder, a suction chamber located above the said pressure chamber, to which suction chamber the inlets of the blowers are connected and, nally, a distribution chamber communicating with the outlets of the blowers. The aforesaid embodiment is characterized in that the pressure chamber is divided by partition walls into sections, and that the medium is directed from the distribution chamber to the pressure chamber through tubes with valves, the tubes corresponding in number to said sections.

The invention will now be described more in detail with reference to the accompanying drawings illustrating by way of an example an embodiment of the device according to the invention.

FIG. l is a fragmentary vertical section through a paper machine constructed in accordance with the present invention;

FIG. 2 is an enlarged fragmentary sectional view taken along line 2-2 of FIG. l; and

FIG. 3 is a section taken along line 3-3 of FIG. 2.

Referring to the drawing 1 designates a cylinder in a paper machine, and 2 is a so called hot air hood placed above said cylinder. Said hood 2 comprises a casing n consisting of a wall 3 congruent with the cylinder prole, two side walls 4 and 5, a roof 6 and two front walls 7 and 8. The wall 3 is made of a single plate while the 3,196,556 Patented July 27, 1965 ICC walls 4 8 consist of two plates with insulating material therebetween. The casing is by partitions 9, 10 and 11 respectively divided into a pressure chamber 12 located adjacent the wall which encloses the cylinder, a suction chamber 13 located above the pressure chamber 12, and a distribution chamber 14. The treatment medium is circulated by means of a plurality of centrifugal blowers 15 arranged in the hot air hood and in direct connection with electromotors 16. Each impeller has a cowl 17 with an inlet 18 communicating with the suction chamber 13 and with an outlet 19 communicating with the distribution chamber 14. The medium is directed from the distribution chamber 14 through a plurality of tubes 20 to the pressure chamber 12. Valves mounted in the tube are indicated by 21. The wall 3 of the pressure chamber facing the cylinder is provided with a plurality of openings 22 adapted for blowing the treatment medium therethrough against the material web. According to the invention, these openings have a hydraulic diameter less than half the distance between the cylinder and said openings. The return of the treatment medium is effected by a plurality of tubes 23 passing through the pressure chamber. According to the invention, the total area of the said tubes shall be at least three times the total area of the blowing holes. In the embodiment shown, the treatment medium is heated by hot gas supplied through a hot air duct 24 which is equipped with a plurality of outlet connections 25 opening at the inlet of the blowers in question. Valves mounted in the said connections 25 are designated 26. The pressure chamber 12 is divided by a plurality of partition walls 27 into sections, each section being connected with the distribution chamber 14 by one of the said vtubes 20, rendering it thus possible to control the distribution of the treatment medium in a direction transverse to the material web, i.e. along the cylinder so that a uniform treatment of the material web is ensured.

We claim:

1. Apparatus for controlling the evaporation intensity in a cylinder paper machine by blowing a treating gas comprising a hot mixture of water vapor and air against a web of paper moving on a cylinder, comprising in combination, means forming an arcuate pressure chamber around a portion of the circumference of the cylinder, said pressure chamber having an inner wall facing the web and parallel thereto and an outer wall, said inner wall having small gas blowing apertures throughout its extent and axially elongated gas return openings at spaced circumferential points between groups of said blowing apertures, said gas return openings being greater in cross section than said blowing apertures, gas return tubes extending through the inner and outer walls of said pressure chamber from said return openings, means forming a suction chamber behind said pressure chamber and a distribution chamber behind the suction chamber, said suction chamber communicating with said return openings, a blower arranged in a dividing wall between said suction chamber and said distribution chamber for moving return gas from said suction chamber to said distribution chamber, a conditioned hot gas supply duct eX- tending axially in said suction chamber and spaced from the walls of the suction chamber and having a valved outlet disposed directly in the intake of said blower and providing for the liow of return gas therearound, a valved supply tube extending through said suction chamber from said distribution chamber to said pressure chamber to supply treating gas to said pressure chamber and an insulating hood enclosing all of said chambers.

2. Apparatus as set forth in claim 1, further characterized by the fact that there are a plurality of pressure chambers along the length of the cylinder and a sep- 'Y 'fr arate supply tube lto each pressure ,chamben each of said supply tubes being provided witha Valve'. whereby tllevrelativepamount of treating gas'supplied to each pres-vV f sure chamber along the length ofthe 'Vcylindergmayv be regulated. y y Y 'v l 3. Apparatus as set forth in claim 2, further'vchari acterized by the fact .that'sai'd sctionvchamber and said distributionk chamber extendrtheV full length of the cyl# inder, that a plurality of blowers are provided along the length of .the cylinder,that .a hoteo'nditionedvgras supply 4. Apparatus as set forth in'clairnk 1, further charv-v Y acterized by the fact that the 4total ovv` area,l offallr'trhe return gas openings and return gas tubes is at least three times the totalY flow area of all of .thegas blowing apern tures.- Y f t 5. Apparatus as set forthvin claim 1, further characterized by the Vfact Vthat Said gas blowing apertures have a hydraulic diameter less than halfthe distance between v the cylinder andsaid apertures.

I p r References Citedbyt'he Examiner Y s y UNITED sTATEsf PATENTS 17/56 'Harris et al, V Y 34-1 2,878,583V4 3/59 l Spooner 34--4122 .2,939,222 6/60.; SVaVlar e 34.122 X 3,012,355 1*-2/61| Allander v- 34-122 X 3,077,675 2/63 Dioliens 34-122 3,078,592 2/*63 Coar 34-122 Y 'FOREIGN PATENTS 1,234,932V 5/670l France.Y t Y 919,229Y V10/54y Germany.

NORMAN YUDKoFF, VPrimary E'xmhiher, 

1. APPARATUS FOR CONTROLLING THE EVAPORATION INTENSITY IN A CYLINDER PAPER MACHINE BY BLOWING A TREATING GAS COMPRISING A HOT MIXTURE OF WATER VAPOR AND AIR AGAINST A WEB OF PAPER MOVING ON A CYLINDER, COMPRISING IN COMBINATION, MEANS FORMING AN ARCURATE PRESSURE CHAMBER AROUND A PORTION OF THE CIRCUMFERENCE OF THE CYLINDER, SAID PRESSURE CHAMBER HAVING AN INNER WALL FACING THE WEB AND PARALLEL THERETO AND AN OUTER WALL, SAID INNER WALL HAVING SMALL GAS BLOWING APERTURES THROUGHOUT ITS EXTENT AND AXIALLY ELONGATED GAS RETURN OPENINGS AT SPACED CIRCUMFERENTIAL POINTS BETWEEN GROUPS OF SAID BLOWING APERTURES, SAID GAS RETURN OPENINGS, BEING GREATER IN CROSS SECTION THAN SAID BLOWING APERTURES, GAS RETURN TUBES EXTENDING THROUGH THE INNER AND OUTER WALLS OF SAID PRESSURE CHAMBER FROM SAID RETURN OPENINGS, MEANS FORMING A SUCTION CHAMBER BEHIND SAID PRESSURE CHAMBER AND A DISTRIBUTION CHAMBER BEHIND THE SUCTION CHAMBER, SAID SUCTION CHAMBER COMMUNICATING WITH SAID RETURN OPENINGS, A BLOWER ARRANGED IN A DIVIDING WALL BETWEEN SAID SUCTION CHAMBER AND SAID DISTRIBUTION CHAMBER FOR MOVING RETURN GAS FROM SAID SUCTION CHAMBER TO SAID DISTRIBUTION CHAMBER, A CONDITIONED HOT GAS SUPPLY DUCT EXTENDING AXIALLY IN SAID SUCTION CHAMBER AND SPACED FROM THE WALLS OF THE SUCTION CHAMBER AND HAVING A VALVED OUTLET DISPOSED DIRECTILY IN THE INTAKE OF SAID BLOWER AND PROVIDING FOR THE FLOW OF RETURN GAS THEREAROUND, A VALVED SUPPLY TUBE EXTENDING THROUGH SAID SUCTION CHAMBER FROM SAID DISTRIBUTION CHAMBER TO SAID PRESSURE CHAMBER TO SUPPLY TREATING GAS TO SAID PRESSURE CHAMBER AND AN INSULATING HOOD ENCLOSING ALL OF SAID CHAMBERS. 